Endoscope assembly with a polarizing filter

ABSTRACT

An endoscope includes an imaging device, a first polarizing filter disposed in front of the imaging device, a light source, and a second polarizing filter disposed in front of the light source.

This application is a continuation-in-part application of U.S. patent application Ser. No. 11/673,470, filed Feb. 9, 2007, the entire disclosure of which is incorporated herein by reference; U.S. patent application Ser. No. 11/673,470 claims the benefit of U.S. Provisional Patent Application No. 60/772,442, filed Feb. 9, 2006; and U.S. patent application Ser. No. 11/673,470 is a continuation-in-part application of U.S. patent application Ser. No. 11/672,020, filed Feb. 6, 2007, of U.S. patent application Ser. No. 11/626,189, filed Jan. 23, 2007, of U.S. patent application Ser. No. 11/609,838, filed Dec. 12, 2006, of U.S. patent application Ser. No. 11/215,660, filed Aug. 29, 2005, and of U.S. patent application Ser. No. 11/030,559, filed Jan. 5, 2005.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an endoscope assembly with a polarizing filter.

BACKGROUND OF THE INVENTION

A conventional endoscope is a medical device comprising a flexible tube, and a camera and a light source mounted on the distal end of the flexible tube. The endoscope is insertable into an internal body cavity through a body orifice to examine the body cavity and tissues for diagnosis. The tube of the endoscope has one or more longitudinal channels, through which an instrument can reach the body cavity to take samples of suspicious tissues or to perform other surgical procedures such as polypectomy.

There are many types of endoscopes, and they are named in relation to the organs or areas with which they are used. For example, gastroscopes are used for examination and treatment of the esophagus, stomach and duodenum; colonoscopes for the colon; bronchoscopes for the bronchi; laparoscopes for the peritoneal cavity; sigmoidoscopes for the rectum and the sigmoid colon; arthroscopes for joints; cystoscopes for the urinary bladder; and angioscopes for the examination of blood vessels.

Each endoscope has a single forward viewing camera mounted at the distal end of the flexible tube to transmit an image to an eyepiece or video camera at the proximal end. The camera is used to assist a medical professional in advancing the endoscope into a body cavity and looking for abnormalities. The camera provides the medical professional with a two-dimensional view from the distal end of the endoscope. To capture an image from a different angle or in a different portion, the endoscope must be repositioned or moved back and forth. Repositioning and movement of the endoscope prolongs the procedure and causes added discomfort, complications, and risks to the patient. Additionally, in an environment similar to the lower gastro-intestinal tract, flexures, tissue folds and unusual geometries of the organ may prevent the endoscope's camera from viewing all areas of the organ. The unseen area may cause a potentially malignant (cancerous) polyp to be missed.

This problem can be overcome by providing an auxiliary camera and an auxiliary light source. The auxiliary camera and light source can be oriented to face the main camera and light source, thus providing an image of areas not viewable by the endoscope's main camera. This arrangement of cameras and light sources can provide both front and rear views of an area or an abnormality. In the case of polypectomy where a polyp is excised by placing a wire loop around the base of the polyp, the camera arrangement allows better placement of the wire loop to minimize damage to the adjacent healthy tissue.

Since the main camera and light source face the auxiliary camera and light source, the main light source interferes with the auxiliary camera, and the auxiliary light source interferes with the main camera. Light interference is the result of the light from a light source being projected directly onto the lens of a camera. This may cause light glare, camera blooming, or over saturation of light, resulting in inferior image quality.

Additionally, because of space constraint, the auxiliary camera and auxiliary light source are typically smaller than the main camera and main light source and use different technologies. Different types of cameras often require different levels of illumination. For example, the main camera generally requires a higher level of illumination and needs a more powerful light source. As a result, the auxiliary camera is often exposed to a significant amount of glare caused by the powerful main light source.

Therefore, there is a need to reduce or prevent light interference between the main camera and main light source and the auxiliary camera and auxiliary light source.

SUMMARY OF THE INVENTION

It is an object of this invention to address the problem of light interference involving the use of imaging devices and light sources for endoscopes. According to one aspect of the invention, the solution lies in the use of one or more polarizing filters including one or more linear or circular polarizing filters.

In accordance with one aspect of the invention, an endoscope assembly includes an imaging device, a light source, and a circular polarizing filter disposed in front of the light source. The circular polarizing filter may be a first circular polarizing filter, and the endoscope assembly may further include a second circular polarizing filter disposed in front of the imaging device. The first and second circular polarizing filters may have opposite orientations. Preferably, each of the opposite polarizing filters includes a retarder, and the retarders of the opposite polarizing filters face each other. Additionally, the light source may be positioned to illuminate a field of view of the imaging device and may face the imaging device.

In accordance with another aspect of the invention, an endoscope assembly includes a light source and a circular polarizing filter disposed in front of the imaging device. The circular polarizing filter may be a first circular polarizing filter, and the endoscope assembly may further include a second circular polarizing filter disposed in front of the light source. Preferably, the first and second circular polarizing filters have opposite orientations. Each of the opposite polarizing filters may include a retarder, and the retarders of the opposite polarizing filters face each other. Additionally, the light source may face the imaging device.

In accordance with yet another aspect of the invention, an endoscope assembly includes an imaging device, a light source, and a circular polarizing filter disposed in front of both the imaging device and the light source. The endoscope assembly may further include a cap, and the circular polarizing filter is disposed on the cap.

In accordance with yet another aspect of the invention, an endoscope assembly includes an imaging device, a first circular polarizing filter disposed in front of the imaging device, a light source, and a second circular polarizing filter disposed in front of the light source. Preferably, the first and second circular polarizing filters have opposite orientations. Each of the first and second polarizing filters may include a retarder, and the retarders of the first and second polarizing filters face each other. Preferably, the imaging device is a first imaging device and the light source is a first light source, and the endoscope assembly includes a second imaging device, a third circular polarizing filter disposed in front of the second imaging device, a second light source, and a fourth circular polarizing filter disposed in front of the second light source. Preferably, the third and fourth circular polarizing filters have opposite orientations. Each of the third and fourth polarizing filters may include a retarder and the retarders of the third and fourth polarizing filters may face each other. In some preferred embodiments, the first light source faces the first imaging device, and the second light source faces the second imaging device. Preferably, the second light source is positioned to illuminate a field of view of the first imaging device, and the first light source is positioned to illuminate a field of view of the second imaging device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of an endoscope with an imaging assembly according to one embodiment of the present invention.

FIG. 2 shows a perspective view of the distal end of an insertion tube of the endoscope of FIG. 1 with a polarizer cap.

FIG. 3 shows a perspective back view of the polarizer cap of FIG. 2.

FIG. 4 shows a perspective view of the imaging assembly shown in FIG. 1.

FIG. 5 shows a perspective view of the distal ends of the endoscope and imaging assembly of FIG. 1 with a cross-sectional view of the lens barrel of the imaging assembly.

FIG. 6 shows a cross-sectional view of a peritoneal cavity with multiple endoscopes.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 illustrates a first exemplary endoscope 10 of the present invention. This endoscope 10 can be used in a variety of medical procedures in which imaging of a body tissue, organ, cavity or lumen is required. The types of procedures include, for example, anoscopy, arthroscopy, bronchoscopy, colonoscopy, cystoscopy, EGD, laparoscopy, and sigmoidoscopy.

The endoscope 10 of FIG. 1 includes an insertion tube 12 and an imaging assembly 14, a section of which is housed inside the insertion tube 12. As shown in FIG. 2, the insertion tube 12 has two longitudinal channels 16. In general, however, the insertion tube 12 may have any number of longitudinal channels. An instrument can reach the body cavity to perform any desired procedures, such as to take samples of suspicious tissues or to perform other surgical procedures such as polypectomy. The instruments may be, for example, a retractable needle for drug injection, hydraulically actuated scissors, clamps, grasping tools, electrocoagulation systems, ultrasound transducers, electrical sensors, heating elements, laser mechanisms and other ablation means. In some embodiments, one of the channels can be used to supply a washing liquid such as water for washing. Another or the same channel may be used to supply a gas, such as CO₂ or air into the organ. The channels 16 may also be used to extract fluids or inject fluids, such as a drug in a liquid carrier, into the body. Various biopsy, drug delivery, and other diagnostic and therapeutic devices may also be inserted via the channels 16 to perform specific functions.

The insertion tube 12 preferably is steerable or has a steerable distal end region 18 as shown in FIG. 1. The length of the distal end region 18 may be any suitable fraction of the length of the insertion tube 12, such as one half, one third, one fourth, one sixth, one tenth, or one twentieth. The insertion tube 12 may have control cables (not shown) for the manipulation of the insertion tube 12. Preferably, the control cables are symmetrically positioned within the insertion tube 12 and extend along the length of the insertion tube 12. The control cables may be anchored at or near the distal end 36 of the insertion tube 12. Each of the control cables may be a Bowden cable, which includes a wire contained in a flexible overlying hollow tube. The wires of the Bowden cables are attached to controls 20 in the handle 22. Using the controls 20, the wires can be pulled to bend the distal end region 18 of the insertion tube 12 in a given direction. The Bowden cables can be used to articulate the distal end region 18 of the insertion tube 12 in different directions.

As shown in FIG. 1, the endoscope 10 may include a control handle 22 connected to the proximal end 24 of the insertion tube 12. Preferably, the control handle 22 has one or more ports and/or valves (not shown) for controlling access to the channels 16 of the insertion tube 12. The ports and/or valves can be air or water valves, suction valves, instrumentation ports, and suction/instrumentation ports. As shown in FIG. 1, the control handle 22 may additionally include buttons 26 for taking pictures with an imaging device on the insertion tube 12, the imaging assembly 14, or both.

The proximal end 28 of the control handle 22 may include an accessory outlet 30 (FIG. 1) that provides fluid communication between the air, water and suction channels and the pumps and related accessories. The same outlet 30 or a different outlet can be used for electrical lines to light and imaging components at the distal end of the endoscope 10.

As shown in FIG. 2, the endoscope 10 also includes a main imaging device 32 and main light sources 34, both of which are disposed at the distal end 36 of the insertion tube 12, and a polarizer cap 38 that is adapted to be mounted on the distal end 36 of the insertion tube 12 to cover the main imaging device 32 and main light sources 34. FIG. 2 shows the polarizer cap 38 removed from the distal end 36 of the insertion tube 12, and FIG. 5 shows the polarizer cap 38 mounted on the distal end 36 of the insertion tube 12.

The main imaging device 32 at the distal end 36 of the insertion tube 12 may include, for example, a lens, single chip sensor, multiple chip sensor or fiber optic implemented devices. The main imaging device 32, in electrical communication with a processor and/or monitor, may provide still images or recorded or live video images. The light sources 34 may be light emitting diodes (LEDs) or fiber optical delivery of light from an external light source. The light sources 34 preferably are equidistant from the main imaging device 32 to provide even illumination. The intensity of each light source 34 can be adjusted to achieve optimum imaging. The circuits for the main imaging device 32 and light sources 34 may be incorporated into a printed circuit board (PCB). As shown in FIG. 2, the insertion tube 12 has a channel 40 for supplying a liquid such as water for cleaning the lenses of the main imaging device 32 and the light sources 34.

The polarizer cap 38, as shown in FIGS. 2 and 3, includes a cylindrical sidewall 42, an end wall 44, and polarizing filters 46, 48 mounted on the end wall 44. The cylindrical sidewall 42 and end wall 44 may form an integral part that is made by injection molding of a suitable biocompatible material such as medical grade plastics. The end wall 44 preferably has an opening 50 for accommodating the polarizing filter 46 for the main imaging device 32. The opening 50 may have any arrangement suitable for retaining the polarizing filter 46. For example, the opening 50 may have a recessed lip for receiving the polarizing filter 46. The polarizing filter 46 can be placed in the recessed lip and fixed there by adhesive bonding or by a mechanical snap fit.

The end wall 44 preferably has an opening 52 for accommodating the polarizing filter 48 for each of the light sources 34. The opening 52 may have any arrangement suitable for retaining the polarizing filter 48. One example of such suitable arrangement is the recessed lip described above. The end wall 44 preferably has an opening 54 for each of the instrument channels 16 so that the cap 38 does not block the channels 16.

The end wall 44 may further include an opening 56 for the channel 40 for supplying a liquid to clean the lenses of the imaging device 32 and the light sources 34. Preferably, the cap 38 has one or more features that allow liquid from the channel 40 to reach over the cap 38 to clean the exterior surfaces of polarizing filters 46, 48. For example, the end wall 44 of the cap 38 may be sufficiently thin to allow the liquid from the channel 40 to reach over the cap 38 to clean the exterior surfaces of polarizing filters 46, 48. Alternatively, the cap 38 may have variable thickness and/or angled features that allow liquid from the channel 40 to reach the polarizing filters 46, 48. Furthermore, the cap 38 may have a ramp, plate or channel that allows liquid from the channel 40 to reach the polarizing filters 46, 48. The locations, configurations and sizes of the openings 50, 52, 54, 56 preferably correspond to the locations, configurations and sizes of the main imaging device 32, light sources 34, channels 16, and clean liquid channel 40, respectively.

As shown in FIG. 3, the cap 38 preferably has a ring 58 located around the inner perimeter of the cap 38. The ring 58 helps secure the cap 38 to the distal end region of the insertion tube 12. In a preferred embodiment, the ring 58 is made from a compressive material such as silicon. Alternatively, the ring 58 can be made from other compressive materials, such as compressive rubbers, polymers and/or foams. The ring 58 may be attached the inner perimeter of the cap 38 by any suitable means such as adhesive bonding, mechanical over molding, or plastic snap features.

The inside diameter of the ring 58 preferably is slightly smaller than the outer diameter of the insertion tube 12 so that the ring 58 can apply a compressive force to the outer surface of the insertion tube 12. This compressive force preferably is sufficient to create the necessary friction force to ensure that the cap 38 remains in the same position and orientation during a medical procedure, yet to allow the cap 38 to be slide on and off of the insertion tube 12 without difficulty.

Alternatively, the cap 38 may have any other type of arrangement for attachment to the insertion tube 12. For example, the cap 38 may have clasps which snap on to the insertion tube 12. In some embodiments, the attachment may be similar to the way in which a suction cap for endoscopic mucosal resection is attached to a colonoscope, as is well known in the art.

The terms “polarizing filter” and “polarizer” as used in this specification refer to any device that blocks one or more components of light while allowing one or more other components to pass through. In some cases, polarizing filters may be made from a material that blocks light waves traveling in all planes from passing through the filter except for light waves propagating in one specific plane of orientation, often referred to as the plane of polarization or the plane of transmission. Polarizing filters may be constructed using various techniques that use light absorption, reflection, scattering or birefringence to block light from passing through the filter that is not orientated parallel with the plane of transmission.

When one polarizing filter is placed in front of another polarizing filter and non-coherent natural white light is passed through the two polarizing filters, the amount of light that passes through the two polarizing filters is proportional to the relative angle of orientation of the two filters. This is because when the polarization plane of the two filters is at the same angle of orientation, the majority of light waves in the plane of transmission will pass through both filters. As one of the filters is rotated, light that is polarized by the first filter is then attenuated or blocked by the second filter. The maximum amount of light reduction or extinction occurs when the polarizing planes of the two filters are orientated at 90° relative to each other. It is common to find polarizing filters that when orientated at 90° provide 99% or greater extinction of light transmission.

Light reduction or extinction by way of a combination of two polarizing filters can similarly be achieved using circular polarizing filters, such as a combination of a left-hand polarizing filter and a right-hand polarizing filter (i.e., a combination of a polarizing filter that rotates the light clockwise and a polarizing filter that rotates the light counter-clockwise).

A circular polarizing filter converts unpolarized light to circularly polarized light. Just as a linear polarizing filter transmits light only in one plane of polarization, a circular polarizer transmits light in only one particular circular orientation of polarization. A circular polarizing filter often has a composite structure that includes a linear polarizing filter and a quarter wave retarder. The retarder axis is oriented at 45° with respect to the axis of the linear polarizing filter. As incident light passes through the composite it is converted to circularly polarized light.

When light is transmitted through a first right-hand circular polarizing filter (which, for instance, is constructed as a linear polarizing filter followed by a quarter wave retarder orientated at 45° with respect to the axis of the linear polarizing filter) and then is transmitted to a second left-hand circular polarizing filter (which, for instance, is constructed as a quarter wave retarder followed by a linear polarizing filter with the retarder oriented at −45° with respect to the axis of the linear polarizing filter), almost no light will pass through the second left-hand circular polarizing filter. This is because the first circular polarizing filter spins the light in one direction and the second polarizing filter only allows light that is spun in the opposite direction to pass through.

As shown in FIGS. 4 and 5, the imaging assembly 14 may include a tubular body 60, a handle 62 connected to the proximal end 61 of the tubular body 60, an auxiliary imaging device 64, a link 66 that provides physical and/or electrical connection between the auxiliary imaging device 64 to the distal end 68 of the tubular body 60, and an auxiliary light source 70 (FIG. 5).

As shown in FIG. 5, the imaging assembly 14 is used to provide an auxiliary imaging device at the distal end of the endoscope 10. To this end, the imaging assembly 14 is placed inside one of the channels 16 of the endoscope's insertion tube 12 with its auxiliary imaging device 64 disposed beyond the distal end 36 of the insertion tube 12. This can be accomplished by first inserting the distal end of the imaging assembly 14 into the insertion tube's channel 16 from the endoscope's handle 18 and then pushing the imaging assembly 14 further into the assembly 14 until the auxiliary imaging device 64 and link 66 of the imaging assembly 14 are positioned outside the distal end 36 of the insertion tube 12 as shown in FIG. 5.

As shown in FIG. 5, the auxiliary imaging device 64 may include a lens barrel 72 having one or more lenses 74, an imaging sensor, and a printed circuit board (PCB). The imaging sensor may be an electronic device which converts light incident on photosensitive semiconductor elements into electrical signals. The imaging sensor may detect either color or black-and-white images. The signals from the imaging sensor can be digitized and used to reproduce an image that is incident on the imaging sensor. Two commonly used types of image sensors are Charge Coupled Devices (CCD) such as a VCC-5774 produced by Sanyo of Osaka, Japan and Complementary Metal Oxide Semiconductor (CMOS) camera chips such as an OVT 6910 produced by OmniVision of Sunnyvale, Calif.

The endoscope 10 preferably includes a polarizing filter 76 placed in front of the auxiliary imaging device 64. The polarizing filter 76 may be placed inside the lens barrel 72. Alternatively, the polarizing filter 76 may be placed directly onto the image sensor itself, or incorporated at various other locations in the lens barrel 72 such as at the end closest to the imaging sensor, or even between the lenses 74. Furthermore, the polarizing filter 76 may be simply placed in front of the auxiliary imaging device.

When the imaging assembly 14 is properly installed in the insertion tube 12, the auxiliary imaging device 64 of the imaging assembly 14 preferably faces backwards towards the main imaging device 32 as illustrated in FIG. 3. The auxiliary imaging device 64 may be oriented so that the auxiliary imaging device 64 and the main imaging device 32 have adjacent or overlapping viewing areas. Alternatively, the auxiliary imaging device 64 may be oriented so that the auxiliary imaging device 64 and the main imaging device 32 simultaneously provide different views of the same area. Preferably, the auxiliary imaging device 64 provides a retrograde view of the area, while the main imaging device 32 provides a front view of the area. However, the auxiliary imaging device 64 could be oriented in other directions to provide other views, including views that are substantially parallel to the axis of the main imaging device 32.

As shown in FIGS. 2 and 3, the link 66 connects the auxiliary imaging device 64 to the distal end 68 of the tubular body 60. Preferably, the link 66 is a flexible link that is at least partially made from a flexible shape memory material that substantially tends to return to its original shape after deformation. Shape memory materials are well known and include shape memory alloys and shape memory polymers. A suitable flexible shape memory material is a shape memory alloy such as nitinol. The flexible link 66 is straightened to allow the distal end of the imaging assembly 14 to be inserted into the proximal end of assembly 14 of the insertion tube 12 and then pushed towards the distal end 36 of the insertion tube 12. When the auxiliary imaging device 64 and flexible link 66 are pushed sufficiently out of the distal end 36 of the insertion tube 12, the flexible link 66 resumes its natural bent configuration as shown in FIG. 3. The natural configuration of the flexible link 66 is the configuration of the flexible link 66 when the flexible link 66 is not subject to any force or stress. When the flexible link 66 resumes its natural bent configuration, the auxiliary imaging device 64 faces substantially back towards the distal end 36 of the insertion tube 12 as shown in FIG. 5.

In the illustrated embodiment, the auxiliary light source 70 (as well as other components) of the imaging assembly 14 is placed on the flexible link 66, in particular on the curved concave portion of the flexible link 66. The auxiliary light source 70 provides illumination for the auxiliary imaging device 64 and may face substantially the same direction as the auxiliary imaging device 64 as shown in FIG. 5.

The endoscope 10 includes another polarizing filter 78 placed in front of the auxiliary light source 70. The polarizing filter 78 may be attached to the auxiliary light source 70 by any suitable means such as adhesive bonding or welding.

The flexible link 66 may be encapsulated or shrouded by flexible tubing, heat-shrinkable tubing, urethanes, rubber or silicon so as to allow smooth profile transition from the tubular body 60 to the imaging device 64. This encapsulation may be translucent to allow light from the light source 70 to project through the encapsulation, or the encapsulation may include a window section around the light source 70.

Since the main imaging device 32 and its light source 34 face the auxiliary imaging device 64 and its light source 70, the light sources 34, 45 of the imaging devices 32, 64 may interfere with the opposing imaging device 64, 32. That is, the main light source 34 may shine directly into auxiliary imaging device 64 and the auxiliary light source 70 may shine directly into the main imaging device 32, degrading both images.

To eliminate or reduce the light interference, the polarization plane of the polarizing filter 46 for the main imaging device 32 may be set at a substantially 90° angle from the polarization plane of the polarizing filter 78 for the auxiliary light source 70. With this arrangement, the light, which is emitted from the auxiliary light source 70 and passes though the polarizing filter 78, may be filtered out by the polarizing filter 46 and may not reach the main imaging device 32. Additionally or alternatively, the polarization plane of the polarizing filter 76 for the auxiliary imaging device 64 may be set at a substantially 90° angle from the polarization plane of the polarizing filters 48 for the main light sources 34. With this arrangement, the light, which is emitted from the main light sources 34 and passes though the polarizing filters 48, may be filtered out by the polarizing filter 76 and may not reach the auxiliary imaging device 64.

Moreover, to provide illumination, the polarization plane of the polarizing filter 46 for the main imaging device 32 may be substantially aligned with the polarization plane of the polarizing filters 48 for the main light sources 34 so that the light, which is emitted from the main light sources 34 and passes though the polarizing filters 48, may pass through the polarizing filter 46 and may be received by the main imaging device 32. Additionally or alternatively, the polarization plane of the polarizing filter 76 for the auxiliary imaging device 64 may be substantially aligned with the polarization plane of the polarizing filter 78 for the auxiliary light source 70 so that the light, which is emitted from the auxiliary light source 70 and passes though the polarizing filter 78, may pass through the polarizing filter 76 and may be received by the auxiliary imaging device 64.

The desired relative orientations of the polarizing filters' the polarization planes, as set forth above, may be achieved in any suitable manner. For example, the polarization planes of the polarizing filters 46, 48 for the main imaging device 32 and main light sources 34 may be aligned and fixed in the polarizer cap 38, and the polarization planes of the polarizing filters 76, 78 for the auxiliary imaging device 64 and auxiliary light source 70 may be aligned and fixed in the imaging assembly 14. Then the imaging assembly 14 may be rotated within the channel 16 of the insertion tube 12 by means of its handle 62 until the polarization planes of the polarizing filters 76,78 in the imaging assembly 14 are at a substantially 90° angle from the polarization planes of the polarizing filters 46, 48 in the polarizer cap 38.

The orientations of the polarizing filters' the polarization planes may be determined and set during attachment by viewing a light with a known polarization passing through polarizing filters. Alternatively, the polarizing filters may have asymmetrical shapes or other locating features so that the orientations of their polarization planes may be readily determined.

Although the polarizing filters 46, 48, 76 and 78 are described above as linear polarizing filters, all or some of them may be circular polarizing filters. In one embodiment, for example, the polarizing filter 76 for the auxiliary imaging device 64 may be a circular polarizing filter of one orientation (such as the left hand), and the polarizing filters 48 for the main light sources 34 may be a circular polarizing filter of the opposite orientation (such as the right hand). Preferably, the retarders of the opposite polarizing filters 48 and 76 face each other. Also the polarizing filter 46 for the main imaging device 32 may be a circular polarizing filter of one orientation, and the polarizing filter 78 for the auxiliary light source 70 may be a circular polarizing filter of the opposite orientation. Preferably, the retarders of the opposite polarizing filters 46 and 78 face each other. In these configurations, the light from a light source is blocked from the image device facing the light source. The use of circular polarizing filters in this configuration allows significant light reduction from glare caused by the light sources without requiring a precise angular alignment or orientation between the two polarizing filters.

The auxiliary imaging device 64 and its light source 70 may be connected to a control box (not shown) via electrical conductors that extend from the imaging device 64 and light source 70; through the link 66, tubular body 60, and handle 62; to the control box. The electrical conductors may carry power and control commands to the auxiliary imaging device 64 and its light source 70 and image signals from the auxiliary imaging device 64 to the control box.

The control box includes at least an image and signal processing device and a housing in which the image and signal processing device is disposed, although the control box can be configured in any suitable manner. The housing may include a control panel and connectors. The control panel includes buttons and knobs for controlling the functionalities of the control box.

The image and signal processing device may include one or more integrated circuits and memory devices along with associated discrete components. The device allows image signals from the imaging devices 32, 64 to be processed for the enhancement of image quality, extraction of still images from the image signals, and conversion of video format for compatibility with the display device.

The control box preferably processes the video image signal from the auxiliary imaging device 64 and transmits it to a display device such as a television or a monitor such as a liquid crystal display monitor. Still images can be captured from the video image signal. The video image or still image may be displayed on the display device. The display device may also include textual data that are used to display information such as patient information, reference numbers, date, and/or time.

The image signal from the main imaging device 32 may also be processed by the control box in the same way that the image signal from the auxiliary imaging device 64 is processed. The images from the main and auxiliary imaging devices 32, 64 may be displayed on two separate monitors or on the same monitor with a split screen.

The control box may further be used to adjust the parameters of the imaging devices 32, 64 and their light sources 34, 70, such as brightness, exposure time and mode settings. The adjustment can be done by writing digital commands to specific registers controlling the parameters. The registers can be addressed by their unique addresses, and digital commands can be read from and written to the registers to change the various parameters. The control box can change the register values by transmitting data commands to the registers.

The control box may additionally be used as an interface to the patient records database. A large number of medical facilities now make use of electronic medical records. During the procedure relevant video and image data may need to be recorded in the patient electronic medical records (EMR) file. The signal processing circuit can convert image and video data to a format suitable for filing in the patient EMR file such as images in .jpeg, tif, or .bmp format among others. The processed signal can be transmitted to the medical professional's computer or the medical facilities server via a cable or dedicated wireless link. A switch on the control panel can be used to enable this transmission. Alternatively the data can be stored with a unique identification for the patient in electronic memory provided in the control box itself. The signal processing circuit can be utilized to convert the video and image data to be compatible with the electronic medical records system used by the medical professional. The processing may include compression of the data. A cable or a wireless link may be used to transmit the data to a computer.

During endoscopy, a technician may first install the polarizer cap 38 onto the endoscope's insertion tube 12. A physician may then insert the endoscope into a body cavity through an orifice of the body. Once the endoscope is inserted, the physician may decide to use the imaging assembly 14 in order to obtain a rear-viewing image of a certain tissue. The physician may straighten the flexible link 66 of the imaging assembly 14 and insert the straightened distal end of the imaging assembly 14 into the channel 16 of the endoscope's insertion tube 12 from the handle 22. The imaging assembly 14 can then be pushed towards the distal end 36 of the insertion tube 12. When the auxiliary imaging device 64 and flexible link 66 are pushed out of the distal end 36 of the insertion tube 12, the flexible link 66 resumes its natural bent configuration as shown in FIG. 2. The main imaging device 32 now captures a front-viewing image, and the auxiliary imaging device 64 simultaneously captures a rear-viewing image of the same area. The physician may then rotate the imaging assembly 14 so that the polarization planes of the polarizing filters 76,78 in the imaging assembly 14 are at a substantially 90° angle from the polarization planes of the polarizing filters 46, 48 in the polarizer cap 38. Once the correct orientation has been established, the physician locks or fixes the orientation of the imaging assembly 14 relative to the insertion tube 12. The physician then continues with the procedure.

The above-described embodiment is merely one of many alternative embodiments of the present invention. In one other alternate embodiment, polarizing filters are placed over only the auxiliary imaging device 64 of the imaging assembly 14 and the main light sources 34 to reduce light interference between them. In this embodiment, a low intensity auxiliary light source 70 may be used for the auxiliary imaging device 64 to alleviate any bright spots that could be seen by the main imaging device 32. This arrangement allows maximum light intake by the main imaging device 32 without light loss caused by a polarizing filter. Similarly, in another alternative embodiment, polarizing filters are placed over only the main imaging device 32 and the auxiliary imaging device 64. These two embodiments are useful depending on the types of imaging sensors used in the endoscope, specifically their light sensitivities, resistance to blooming, and dynamic ranges, as well as depending on the types of light sources used in the endoscope and their illumination intensities and/or wave length spectrums.

In another alternate embodiment, the main imaging device 32 and main light sources 34 may share a polarizing filter. For example, the polarizer cap mounted on the distal end of the insertion tube may have a large polarizing filter approximately the size of the cap' end wall. This large filter may have openings for the channels 16 of the insertion tube 12. Alternatively, the filter may occupy only the area of the cap's end wall in front of the main imaging device 32 and main light sources 34. This embodiment allows for the orientation of the polarization plane in front of the main imaging device 32 and main light sources 34 to be precisely orientated.

In general, a polarizing filter may be placed in a cap mounted in front of an imaging device, placed in the lens assembly of the imaging device, or attached to the front of the imaging device. Various techniques for attachment may be used, such as ring and clamp arrangements, snap fit or plastic friction fit arrangements, or even permanent bonding. Alternatively, polarizing filters may be placed along the optical path of the fiber optic bundles that run along the length of the endoscope, or even placed in an external light source box.

In still another alternate embodiment, a cap with one or more polarizing filters, similar to the cap 38 shown in FIGS. 2 and 3, may be placed on the auxiliary imaging device 64.

In yet another alternate embodiment, as shown in FIG. 6, when multiple endoscopes 80, 82, which may be considered as an endoscope assembly, are used during a procedure, such as during laparoscopy or arthroscopy, a polarizer cap 84, 86 may be placed over one or more of the endoscopes 80, 82 to reduce light interference caused by endoscopes 80, 82. In FIG. 6, the endoscopes 80, 82 are inserted into a peritoneal cavity 88. Preferably, at least one of the endoscopes 80, 82 has a channel that allows a surgical tool 90 to access the peritoneal cavity 88. In the illustrated embodiment, one or more of the endoscopes 80, 82 may have a light source. In some cases, each and every one of the endoscopes 80, 82 has a light source. Similarly, one or more of the endoscopes 80, 82 may have an imaging device. In some cases, each and every one of the endoscopes 80, 82 has an imaging device. In one particular case, only one of the endoscopes has a light source, while each of the other endoscopes has only an imaging device. In the illustrated embodiment, the polarizing filters of the same cap 84, 86 may have the same plane of polarization, and the polarizing filters of the different caps 84, 86 may have different planes of polarization. Alternatively, the caps may have the same plane of polarization but a physician can rotate one or more endoscopes to the appropriate orientations. If only two endoscopes 80, 82 are used, the two caps 84, 86 may have their planes of polarization orientated at 90° from one another. If only three endoscopes are used, the three caps may have polarization planes orientated at 120° relative to one another so as to provide a significant cancellation of light interference at each endoscope.

In a further alternate embodiment, the endoscope may have orientation arrangements on both the polarizer cap and the imaging assembly such that the orientation between polarizing filters may be easily adjusted. One such embodiment includes a small magnet that is permanently fixed to the polarizer cap, and a metallic element fixed to the imaging assembly. The magnet may be a rare earth magnet such as a Neodymium Iron Boron type permanent magnet. The orientation of the magnet and metallic element is designed such that the magnetic field generated by the magnet will attract the metallic element most strongly when the polarizing filters are properly aligned. In this manner, when the metallic element is in close proximity to the magnet, it will naturally be pulled by the magnet into the correct position. Furthermore, when the magnet and metallic element come into contact, an attachment is formed which resists change of orientation and maintains the proper orientation between the polarizing filters. Only when a substantial force is applied, such as when the physician forcefully advancing the imaging assembly, will the magnetic attachment be broken, allowing the physician to re-align or remove the imaging assembly. Alternatively, the magnet may be placed in the imaging assembly and a metallic element may be located on the cap. Furthermore, magnets may be used on both the imaging assembly and the cap.

In still a further alternate embodiment, the orientation features include a feature, such as a pin, rod or geometric feature, affixed to and protruding slightly away from the imaging assembly, and a feature, such as a cup and tube, on the polarizer cap that mates with the corresponding feature on the imaging assembly. The features may be made from a compressive material such as rubber so that when the two features are engaged a substantial force is needed to break the engagement. In this manner, the physician would first slide the imaging assembly past the distal end of the insertion tube and then, under the guidance of the auxiliary imaging device, rotate the imaging assembly to achieve the correct relative orientation between the polarizing filters. When the correct relative orientation between the polarizing filters is achieved, the physician may retract the imaging assembly so that the two features engage and lock together. To later disengage the features, the physician may forcefully advance the imaging assembly.

In yet a further alternate embodiment, the distal end of the imaging assembly includes a mechanism that can fix the position of the imaging assembly in the channel of the insertion tube. Such a mechanism may include the use of inflatable balloons, springs that are actuated via guide-wires, mechanical engagement arrangements, or frictional methods such as large diameter compressive regions incorporating rubber or foam.

In the present application, the terms “insertion tube,” “imaging assembly” and “endoscope” are interchangeable, may have the same or similar meanings, and may have the same or similar features and functions. Different terms are used in the application for ease of identification and description. Additionally, such a description should not be used to limit the breadth of the application. The use of “insertion tube,” “imaging assembly”, or “endoscope” merely refers to possible types of instruments in the broad field of endoscopy and the invention may be applied to many forms of endoscopes and medical imaging devices.

Furthermore, the configuration of one endoscope that is inserted through the channel of another endoscope (such as the imaging catheter being inserted through the main endoscope as described in the preferred embodiments) can be referred to as a major-minor endoscope configuration, where the larger diameter endoscope is referred to as the major endoscope and the smaller diameter endoscope as the minor endoscope. 

1. An endoscope assembly, comprising: an imaging device; a light source; and a circular polarizing filter disposed in front of the light source.
 2. The endoscope assembly of claim 1, wherein the circular polarizing filter is a first circular polarizing filter, the endoscope assembly further comprising a second circular polarizing filter disposed in front of the imaging device, wherein the first and second circular polarizing filters have opposite orientations.
 3. The endoscope assembly of claim 2, wherein each of the opposite circular polarizing filters includes a retarder and wherein the retarders of the opposite circular polarizing filters face each other.
 4. The endoscope assembly of claim 1, wherein the light source is positioned to illuminate a field of view of the imaging device.
 5. The endoscope assembly of claim 1, wherein the light source faces the imaging device.
 6. An endoscope assembly, comprising: an imaging device; a light source; and a circular polarizing filter disposed in front of the imaging device.
 7. The endoscope assembly of claim 6, wherein the circular polarizing filter is a first circular polarizing filter, the endoscope assembly further comprising a second circular polarizing filter disposed in front of the light source, wherein the first and second circular polarizing filters have opposite orientations.
 8. The endoscope assembly of claim 7, wherein each of the opposite polarizing filters includes a retarder and wherein the retarders of the opposite polarizing filters face each other.
 9. The endoscope assembly of claim 6, wherein the light source faces the imaging device.
 10. An endoscope assembly, comprising: an imaging device; a light source; and a circular polarizing filter disposed in front of both the imaging device and the light source.
 11. The endoscope assembly of claim 10, further comprising a cap, wherein the circular polarizing filter is disposed on the cap.
 12. An endoscope assembly, comprising: an imaging device; a first circular polarizing filter disposed in front of the imaging device; a light source; and a second circular polarizing filter disposed in front of the light source, wherein the first and second circular polarizing filters have opposite orientations.
 13. The endoscope assembly of claim 12, wherein each of the first and second circular polarizing filters includes a retarder and wherein the retarders of the first and second circular polarizing filters face each other.
 14. The endoscope assembly of claim 12, wherein the imaging device is a first imaging device and the light source is a first light source, the endoscope assembly further comprising, a second imaging device; a third circular polarizing filter disposed in front of the second imaging device; a second light source; and a fourth circular polarizing filter disposed in front of the second light source, wherein the third and fourth circular polarizing filters have opposite orientations.
 15. The endoscope assembly of claim 12, wherein each of the third and fourth circular polarizing filters includes a retarder and wherein the retarders of the third and fourth circular polarizing filters face each other.
 16. The endoscope assembly of claim 14, wherein the first light source faces the first imaging device, and wherein the second light source faces the second imaging device.
 17. The endoscope assembly of claim 14, wherein the second light source is positioned to illuminate a field of view of the first imaging device, and wherein the first light source is positioned to illuminate a field of view of the second imaging device. 